1. Field of the invention
This invention relates to combination locks and has particular reference to locks for use in doors, requiring proper setting of a series of code pins arranged around a knob spindle to enable release of the lock.
2. Description of the prior art
Examples of locks of the above type are disclosed in U.S. Pat. Nos. 436,597 to J. J. Deal; 1,530,361 to H. S. Standen; and 4,191,035 to G. Hatch.
Although such prior art locks obviate the need for using keys to release a lock, they present certain disadvantages which have precluded their widespread adoption heretofore, namely, in part, they cannot be released from inside a building while remaining locked from the outside. Also, in such prior art locks, the code pins, after being set to release the lock, must be reset by a subsequent manual operation so that the prescribed combination necessary to release the lock cannot be discerned by unauthorized persons. Further, none of such prior locks, to applicant's knowledge, can be mounted in doors having modern standard size bolt and lock openings therein without extensively changing or remortising of the door.